Diesel particulates contained in diesel engine exhaust gas are formed by condensation and agglomeration of unburned components of fuel and lubricating oil, and are agglomerates in which an organic solvent-soluble organosoluble fraction (hereinafter, abbreviated as SOF) and an organic solvent-insoluble fraction (hereinafter, abbreviated as ISOF) including sulfate, nitrates, elemental carbon and metals are mixed together in a complex manner. The composition of such particulates is known to be affected strongly by various factors such as fuel, lubricating oil, engine type and operation conditions. The polycyclic aromatic hydrocarbons and the nitropolycyclic aromatic hydrocarbons are contained in the SOF of diesel particulates, and although the contents thereof are extremely small, the methods for analyzing the hydrocarbons have been recently investigated because of their high carcinogenicity (see, for example, Patent Documents 1 and 2). Because the contents of these substances are small, these substances cannot be detected unless a large number of interfering substances are eliminated to enhance the analytical sensitivity and precision. For that purpose, the sample is required to be subjected to a preanalysis treatment to eliminate interfering components in such a way that the sample adapts to the targets to be analyzed.
Patent Document 1: Japanese patent Application No. 2003-275806
Patent Document 2: Japanese Patent Laid-Open No. 2001-21497